I understand now that the Wayback Machine has nothing to do with the Internet Archive. (I am an advocate for simplicity and not assuming expertise from anyone. The people behind the scenes should make a point of adding a notation on the Wayback Machine page where this information appears up-front so that it can be read by those who upload files with WM.)
I took the plunge and turned web pages into .pdf files and uploaded them to IA. Unfortunately, I am experiencing a problem with one of them. I accidentally uploaded the draft copy and didn't realize it until later. There is nothing on the "change the files" screen that shows a link to "UPDATE" a file (the only selection given is "upload new files to item") so I uploaded the correct copy hoping that it's the way to update the previous version, but from what I can tell it's not happening. The server gave me a "this file has already been uploaded" message (or something to that effect). I'll keep at it until either the upload server stops bucking and updates the file -- or I delete everything and try an upload again from scratch.